The deuterodesulfurization (DDS) of thiophene was investigated over PbMo6S8 at 400°C using a flow-microreactor. Evidence indicates that 1,3-butadiene (BDE) is the first desulfurized product; its deuterium content was established by 2H NMR and mass spectrometries. At different levels of thiophene conversion (0.86-10.2%), the amount of deuterium incorporated into BDE remains constant at 3.47 D atoms per BDE molecule. Unconverted thiophene incorporates 0.42 D atoms at 10.2% thiophene conversion but only 0.05 D atoms at 0.86% conversion. Reaction of 2,5-dihydrothiophene (2,5-DHT) with D2 at 400°C over PbMo6S8 liberates BDE as the only hydrocarbon product. This BDE incorporates no deuterium. Thiophene and H2S effectively inhibit both BDE hydrogenation and deuterium exchange. The results indicate that during the DDS process, a total of 3.2 deuterium atoms are incorporated into the BDE; 0.83 D are in the DA-position while 1.2 D are in each of the DB-and DC-positions. Several HDS mechanisms proposed in the literature are consistent with these results; two are not. Details of all of these mechanisms are discussed.
- Chevrel phase catalyst
- Deuterium labelling
ASJC Scopus subject areas
- Process Chemistry and Technology
- Physical and Theoretical Chemistry